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Volume 10, Issue 4
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Yutaka ASAHI1962 Volume 10 Issue 4 Pages 135-141
Published: 1962
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPrinciple and instrument of electron spin resonance (ESR) and its application on polarography are reviewed. Generation of free radicals by a controlled potential electrolysis is preferable to that by chemical reduction because there are no complicate interactions between electron and reagent. Maki showed that it was possible to observe directly the one electron transfere process in the electrolytic reduction of nitrobenzene to the negativeion in a solution of acetonitrile with tetra-n-propyl ammonium perchlorate. ESR of the free radical of nitrobenzene consists of 54 hyperfine structures as shown in Fig. 2. The coupling constants of the nitrobenzene derivatives are given in Table 2. Aromatic hydrocarbons such as anthracene undergo a 2 electron reduction in an aqueous solution but an 1 electron reduction in a non aqueous solution. The formation of a free radical by the electrolysis of anthracene is observed by ESR at liquid nitrogen temperature. Stable semiquinones are also generated by electrolysis. It is postulated by ESR that an odd electron in reduced nitroparaffins distributes not only in the nitro group but also in the alfa methylene. In the reduction product of tetracyanoethylene, the interaction among an odd electron, 13C and 13N is postulated. Possibilities of the application of ESR on inorganic polarography are suggested.View full abstractDownload PDF (942K) -
Mltsugl SENDA, Mltsuko SENDA, Isamu TACHI1962 Volume 10 Issue 4 Pages 142-153
Published: 1962
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESS -
Hiroyuki NEZU1962 Volume 10 Issue 4 Pages 154-162
Published: 1962
Released on J-STAGE: October 21, 2011
JOURNAL FREE ACCESSThe Brdicka catalytic reduction of hydrogen at the dropping mercury electrode fundamentally differs from the reduction in the case of usual diffusion currents. This phenomenon has been studied in detail by many authors for the last thirty years. Despite the vast experimental data thus accumulated, no decisive conclusion seems to have been drawn as to the nature of the species in the electrolytic solutions. This catalytic reduction apparently requires the presence of sulfhydryl group and is best observed in an ammoniaammonium chloride buffer solution containing cobalt. Compound such as cysteine or cystine produces under these conditions a single wave with a rounded maximum. The most difficult point in the interpretation of the whole catalytic electrode process is in the elucidation of the role of cobalt. Brdicka has assumed that the cysteinatocobaltate complex formed in the electrolytic solution might facilitate the deposition of hydrogen from the solution. This assumption is based on the structure of cysteinatocobaltate which was given by Schubert in 1931. But Brdicka did not show any experimental evidence to verify the assumption.
As the catalytic action of bis-cyteinatocobaltate does not seem to have been firmly established, this paper describes a work carried out to learn more about this complex. On the basis of polarographic and spectrophotometric methods, it is suggested that the cysteinatocobaltate (II) chelate is the essential substance to produce the catalytic wave of cysteine in ammoniacal solution containing divalent cobalt.View full abstractDownload PDF (2348K) -
Mutsuaki SHINAGAWA, Hiroyuki NEZU, Tetsuya YAMADA1962 Volume 10 Issue 4 Pages 163-171
Published: 1962
Released on J-STAGE: October 21, 2011
JOURNAL FREE ACCESSIn continuation of our studies of the Brdicka catalytic wave of hydrogen it became necessary to know more about the electrode reaction which produces the catalytic wave due to sulf hydryl groups in the presence of the ammoniacal buffered cobalt solution. The most delicate point in the interpretation of the whole catalytic electrode process involved in the polarographic "protein wave" consists in the elucidation of the role of cobalt. Therefore, the present study has been conducted in order to examine the following three points ; 1) How does the net reduction of cobalt ion take place during the period of its own maximum wave? 2) The cobaltous wave is shifted to more positive potentials by the presence of cystine or serum protein and under some conditions it becomes into two steps. During the period of such cobalt wave, how does the net reduction of cobalt ion take place? 3) During the period of the catalytic wave, how does the net reduction of cobalt ion take place?
In the present investigation, the measurements of the net amounts of reduced cobalt are carried out by the method of radiometric polarography using Love's method' after improving several points. Radioactivity per one drop of mercury divided by drop time is plotted against the applied potential. Thus, the radioactivity-potential curve illustrates the net reduction of cobalt ion to form amalgam and can be compared with the corresponding ordinary polarogram finding no special reduction of cobalt during the period of the catalytic wave of hydrogen.View full abstractDownload PDF (875K)
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